silverton Posted June 23, 2011 Share Posted June 23, 2011 It should, actually, be turned all the way clockwise in a closed position. Link to comment Share on other sites More sharing options...
Kyle94 Posted June 23, 2011 Author Share Posted June 23, 2011 Well it was turned pretty far out. Lol. Wonder how that happened. Link to comment Share on other sites More sharing options...
silverton Posted June 23, 2011 Share Posted June 23, 2011 Wonder how that happened. Someone didn't know what they were doing obviously. Link to comment Share on other sites More sharing options...
Kyle94 Posted June 23, 2011 Author Share Posted June 23, 2011 Somethin. Now I jeed to get new sparkplugs I think. Link to comment Share on other sites More sharing options...
nismothunder Posted June 23, 2011 Share Posted June 23, 2011 the canister next to the air cleaner box has given me idle problems before.....I've heard these are common problems with this engine. i believe its called an evap canister. part of the emission system. Its a common problem with all older engines with Evap systems (Evaporative Emissions Control system) All it does is trap and store fuel vapor that evaporated from the fuel tank, throttle body and intake while being stored or at idle. Make sure the canister isnt cracked, has missing hoses, hoses that are plumbed in propely or a bad vavle. Link to comment Share on other sites More sharing options...
VW_Factor Posted June 28, 2011 Share Posted June 28, 2011 It should, actually, be turned all the way clockwise in a closed position. The IAC valve "idle screw" should be all the way closed normally? (or clockwise?) Link to comment Share on other sites More sharing options...
silverton Posted June 28, 2011 Share Posted June 28, 2011 Turning it clockwise is closed, counter clockwise is open. And yes, it should be closed, if not just a HAIR open. the ECU should be able to adjust the idle automatically with no change needed from the user. If it's not adjusting automagically then there is a sensor not quite doing its job and messing with the idle screw is a bandaid for that. Link to comment Share on other sites More sharing options...
VW_Factor Posted June 29, 2011 Share Posted June 29, 2011 (edited) Turning it clockwise is closed, counter clockwise is open. And yes, it should be closed, if not just a HAIR open. the ECU should be able to adjust the idle automatically with no change needed from the user. If it's not adjusting automagically then there is a sensor not quite doing its job and messing with the idle screw is a bandaid for that. What all sensors regulate the idle speed? Edit : I ask, because when I replaced my IAC some time ago, and while I do not know where the screw was set when I installed it, I backed it out I think about 2 turns. What I had was a slow response to external things such as park to drive.. A/C kicked on.. Seemed to take a while to adjust idle properly. Backing the screw out seemed to speed this up to where it is not noticeable. However I do run into times where idle will stay high for long periods of time, or when "mid temp" I'll get a small skip or miss in the engine that seems random. Otherwise, the engine runs awesome. Wires have been replaced a bit ago, along with plugs. MAF was cleaned and is in good working order. The connector on the "tower" near the IAC is a bit on the loose side as part of the connector is broken. I am unsure as that what the "tower" sensor is. Edited June 29, 2011 by VW_Factor Link to comment Share on other sites More sharing options...
sewebster Posted June 29, 2011 Share Posted June 29, 2011 (edited) The ECU controls the idle speed with the AAC valve, which is basically a little electrically actuated plunger in the IAA body. The screw next to it just pushes another plunger in which can also serve to restrict flow. The "tower" is the air regulator. It allows extra air to flow into the intake when the engine is cold to increase idle speed. I know my screw is turned all the way out and my idle is fine (except occasionally it drops too low, but I don't think this is a screw issue). I guess now I'm curious to see if anything would change if I turned it in. I know that before I used the screw to lower the idle, but I later found a vacuum leak. I turned the screw all the way out to try to increase idle before when I had an oil pump problem but no dice. edit: if your engine idles too high it could be the air regulator, a vacuum leak, or a throttle stuck open issue. In terms of sensors that control idle, I would guess that the only thing would be the crank angle sensor, which tells the ECU how fast the engine is turning? Edited June 29, 2011 by sewebster Link to comment Share on other sites More sharing options...
VW_Factor Posted June 29, 2011 Share Posted June 29, 2011 The idle might be a bit high, but only occasionally, and its intermittent. 1 stop light, it may act up, and 3 minutes later, its acting normal. Knowing the "tower" is the air regulator, I have a feeling that just may be my problem as the connector is looseish. Vacuum leaks, throttle stuck open.. I checked for that stuff, and all seems to be in order. Link to comment Share on other sites More sharing options...
Kingman Posted June 29, 2011 Share Posted June 29, 2011 Crank Angle Sensor has nothing to do with idle. There's also the IACV that tends to get a little sporadic with age. Link to comment Share on other sites More sharing options...
sewebster Posted June 29, 2011 Share Posted June 29, 2011 Crank Angle Sensor has nothing to do with idle. There's also the IACV that tends to get a little sporadic with age. I'm pretty sure that the ECU controls idle at 750 rpm... so it has to know how fast the engine is spinning to do that, right? When you say "IACV" do you mean idle air control valve? Maybe I'm messing up the terminology, but I think that's what I mean when I say AAC the electric plunger in the idle control body. Just found this page which does a good job talking about this stuff. The air regulator should only affect things when it's cold, but I actually don't know what the connector is for. Theoretically it could be a fully mechanically operated valve. Link to comment Share on other sites More sharing options...
Kingman Posted June 29, 2011 Share Posted June 29, 2011 Yes, the CAS informs the computer of how fast the engine is rotating in order to produce spark and fuel at the proper time. It also feeds the ECU battery voltage. However, the sensor doesn't mess up or "misread" - it will only fail entirely. And when it does, there goes your fuel and spark. The AAC valve is for cold start only, and it is it's own piece. I think. I get somewhat crossed up dealing with NA and turbo Z31s as well as TBI and MPFI Pathfinders. Link to comment Share on other sites More sharing options...
silverton Posted June 29, 2011 Share Posted June 29, 2011 idle is controlled by the temperature of the air, and the temperature of the coolant. Link to comment Share on other sites More sharing options...
sewebster Posted June 29, 2011 Share Posted June 29, 2011 The AAC valve is for cold start only, and it is it's own piece. I think. I get somewhat crossed up dealing with NA and turbo Z31s as well as TBI and MPFI Pathfinders. Ok, I'm fairly confident that for MPFI pathfinders (because I read the FSM last night) that the "air regulator" (the tower thing) is for cold start only and the AAC valve is the thing in the idle adjust body that controls idle all the time. But anyway, we're just talking terminology and acronyms now. Link to comment Share on other sites More sharing options...
Alkorahil Posted June 29, 2011 Share Posted June 29, 2011 (edited) The 'tower thing' is the AAC regulator. I dont see this go out much, I do see the AAC on the VG30 though. Try this: Unplug the AAC. (not the regulator) You can reach back behind the back of the manifolod and unplug it. Id recommend doing this when the vehicle is not hot. You can eyeball the connector by looking from the driver side fender. When you start the engine as soon as the engine 'catches' and starts, floor the accelorator. This makes the ECU bypass the AAC. IF the idle evens out at around 750 RPM then you probably have a bad AAC. As mentioned above the AAC can/will go out with age. The AAC has a butterfly valve inside and I would suspect it is probably corroded so it will not close/open and is also why it wont adjust on the idle adjustment screw. Edited June 29, 2011 by Alkorahil Link to comment Share on other sites More sharing options...
sewebster Posted June 30, 2011 Share Posted June 30, 2011 You can disconnect the AAC valve at the connection on the passenger valve cover too, I think it's the only connector there with 2 wires. No reaching Link to comment Share on other sites More sharing options...
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